Method and apparatus for lining wells



April 10, 1962 E. R. JENNINGS METHOD AND APPARATUS FOR LINING WELLS Filed Oct. 27, 1958 EARL R. JENNINGS INVENTOR.

or to the casing already in the well.

United States Patent 3,028,915 METHSD AND APPARATUS FUR LHQING WELLS Earl R. Jennings, Tulsa, Okla, assignor to Pan American Petroleum Corporation, Tulsa, Okla, a corporation of Delaware Filed Oct. 27, 1958, Ser. No. 769,941 9 Claims. (Cl. 166-46) This invention relates to producing a liner in a well. More particularly, this invention is directed to an improved well liner and a method and apparatus for placing it in a well and especially in a well casing to plug holes or perforations in the casing. This application is a continuation-in-part of my application Serial Number 702,466,

led December 12, 1957, and now abandoned.

Liners have been placed in wells for many purposes including the recovery of circulation in a drilling well, shutting off the flow of undesirable fluids into a well, plugging casing leaks or perforations, and the like. A liner is typically shorter than the depth of the well and small enough to pass through the well and any casing therein. It is lowered to the proper elevation in the well where the liner is sealed at one or both ends to the well wall Such liners have generally been difficult to install and seal in a well, have reduced the diameter of the well and accordingly the producing efficiency of the well, and have generally been too expensive to be widely acceptable in the art.

It is, therefore, an object of this invention to provide a liner for a well which will not materially decrease the diameter of the well, which can be set in the well with a minimum of expense, and which will make a fluid-tight seal with the well Wall or with the casing therein. It is another object of this invention to provide an improved method and apparatus for setting such a liner in a well. Other objects of this invention will become apparent from the following description. In this description reference will be made to the accompanying drawings in which:

FIGURE 1 shows partially in vertically cross section, an apparatus suitable for setting my improved liner in a well;

FIGURE 2 is a cross-sectional view taken on the line 2-2 of FIGURE 1; and

FIGURE 3 is a cross-sectional view similar to FIGURE 2 showing the improved liner and liner-setting apparatus in an expanded position in a conduit.

This invention may be described in brief as a fiber reinforced plastic well liner. It includes an improved proceedure and apparatus for setting and curing a plastic liner in place in a well. An important element of this invention is an expandable setting tool for placing such liners in wells.

Reference will now be made to the drawings for a more detailed description of the procedure for making up a fiber reinforced plastic well liner and an apparatus suitable for running and setting the liner. The liner setting tool includes primarily an expandable mandrel which is made up at the surface and attached to the lower end of a tubing string 11. This mandrel includes a resilient expansion member such as a rubber tube 12. This tube may be expanded diametrically by compressing it axially but preferably the expandable element is expanded by inflating it with a gas or liquid under pressure. Longitudinal or spiral reinforcing cords may be molded in the tube to increase its strength. This tube may be of any length, typically between about one and about 50 feet or more, depending upon the length of the liner which is to be placed in a well. The wall thickness of the tube may also be varied over a substantial range depending upon the diameter and particularly upon the pressure used to inflate the tube. A thickness of from about inch to about one inch, typically about /2-% inch for an inflation pressure of about -500 pounds has been found satisfactory. The external diameter of the tube unstressed is desirably about 1-2 inches less than the diameter of the casing or well in which the liner is to be placed or through which the liner is to be run so that the resin-impregnated fiber or fabric sleeve 13, which is built up around this tube and which eventually will become the liner can be lowered easily through the well to the position at which the liner is to be set.

This elastic or expansible tube is connected to a tubular body 14 by upper and lower clamps 15 and 16, respectively, which hermetically seal the tube to the body so that fluid pressure applied internally will expand or inflate the tube. The body has a central perforated section 17 threaded to the upper head 18 and to the lower head 19. This section has one or more fluid passages or perforations 21 which provide fluid communication between the inside of the tubular body and the inside of the tube 12 so that the tube may be inflated by the application of fluid pressure via the tubing string and the body. A fluid bypass conduit 22, connected as by welding, rolling, or the like at the upper end to upper head 18 and at the lower end to lower head 19, extends through the body and terminates outside the body above and below the ends of the tube 12 so that fluid pressure in the annular space outside the mandrel above and below the tube will be equalized at all times, particularly when the tube is expanded and while the resin in the liner is curing as hereinafter described. A knockout or shear plug 23 is threaded into the body 14 above the by-pass conduit 22. This tubular plug has a closed end 24 protruding a substantial distance inside the body. This shear plug, as will be described in greater detail hereinafter, provides a means for equalizing the pressure inside the tube with the pressure outside the tube so that at the proper time the tube will contract to its normal or unstressed diameter and can be removed from the inside of the liner.

A combination standing and relief valve unit 25 is located at the lower end of the body 14. A standing valve seat 26 is threaded into the lower end of lower head 19. A tubular standing valve member 27 or tubing loading valve, comprising a part of the combination valve unit 25, in cooperation with this seat, permits the Well fluids to enter the body 14 through the annular opening 28 as the mandrel is lowered into the well thereby fillingthetubing with well liquids and equalizing the pressure in the man: drel with the external or well pressure. The lower end of the tubular standing valve member 27 is threaded into a movable relief valve cage 29. A ball valve member 31 together with the lower end of the tubular valve member form a relief valve. This'ball valve member is seated in and held against the lower end of the tubular standing valve member 27 by spring 32.. This ball valve member prevents well fluids from entering the lower end of the tubular standing valve member 27 but permits fluids tobe released from inside the body when the differential pressure across the relief valve is greater than the pressure at which this relief valve is set to open by the adjustment of spring tension adjusting screw 33. screw is set at the surface to maintain sufficient differential pressure. typically 100400 p.s.i., to inflate the rubber tube but to open before the differential pressure is great enough to rupture the tube. This screw is held in a fixed position in the relief valve cage 29 by a lock nut 34. Fins 35 on the upper end of the cage 29 provide a fluid passage between the standing valve seat 26 and the relief valve cage when the standing valve member is in its extreme upper position.

A relief valve housing in the form-of a collar 36 is connected at the upper end to the lower body head 19 and at the lower end to a lower tubing string extension 37.

The adjusting A centraiizer 38 may be mounted on the lower tubing string extension near the mandrel, on the tubing string above the mandrel, or centralizers may be placed both above and below the mandrel to protect the sleeve 13 from rubbing against the casing or the well wall as the sleeve and mandrel are lowered into the well. In some cases for the protection of the sleeve as it is run in the well, the lower centralizer may take the form of a solid gauge or a junk pusher larger than the assembled mandrel and sleeve.

In operation, the mandrel is assembled preferably in substantially the form described above. With the mandrel assembled at the surface, the sleeve 13 which will eventually form the well liner is made up on the expandable tube 12 in substantially the following manner. The tube is first treated on the external surface with a parting compound to prevent the base resins from adhering to the tube surface. A heavy coating of wax such as a high-softening-point carnauba wax is first applied to the complete surface to be covered by the sleeve, allowed to harden, and then buffed smooth. Various silicone moldreleasing agents may additionally or alternatively be applied to the surface of the tube so that the cured resin will not adhere and the setting tool may be released from the liner and withdrawn from the well. A first layer of natural or synthetic fabric 39, preferably a piece of relatively coarse woven nylon or glass cloth such as woven roving as long as the desired l ner and as wide as the periphery of the well, is first impregnated with a resin, desirably a thermosetting resin, and then wrapped around the expansible tube. It may be wound around the tube spirally, i.e., with the edges overlapping, or it may be formed into a tube with a diameter equal to the casing or well diameter and folded or pleated around the tube with the pleats or corrugations running longitudinally of the tube. in some cases, it is desirabie in addition to or in lieu of impregnating this fabric with the thermosettiug resin to brush, trowel, or butter a viscous resin, containing sufficient finely divided fillers such as fullers earth to make it of trowel consistency and a small amount (25%) of a thickening or thixotroping agent such as a porous silica aerogel, on the fabric either before or after the fabric is placed on the expansible tube. This additional resin is desirably more viscous than the resin with which the cloth is initially impregnated. The resin may be made viscous by the use of fillers such as silica flour as is well known in this art. In some cases, a second and even a third layer of this impregnated and/or coated fabric is placed on the expansible tube in the same manner. The number of layers depends generally upon the thickness and strength of the liner desired, upon the conditions or" the casing surface or well wall, and the amount of resin which is to be used. The greater the number of layers the more resin that can be applied and the stronger the liner. The number of layers is. however, limited in some cases by the permissible thickness of the liner. Each of these laminae may be held in place by lightly tacking the lapped ends or by a binding which is wrapped around the tube and the fabric. After the resin-saturated fabric 39 has thus been placed on the tube, it is covered and surrounded by a more rigid but permeable woven fabric or screen 4-3 such as a coarse woven glass or metal screen like hardware cloth. Four to 50 mesh, typically about 20 mesh, hardware or glass cloth is preferred. Owens-Corning Fiberglas Corporations square-woven fabric No. 162 is an example of a preferred glass fabric. Like the inner layers of plastic impregnated fabric, this outer screen is usually first saturated with the resin and then wrapped around the mandrel and the inner layer or layers of fabric thereon. it is also lightly tacked to hold it in position. This screen, also like the fabric underneath, is desirably as long as the ultimate liner and is as wide as the circumference of the pipe to be patched. It may be wrapped around the tube and underlying fabric spirally, i.e., with the edges overlapping, or it may be formed into a tube with a diameter equal to the casing or well diameter and folded or pleated around the tube with the pleats or corrugations running longitudinally of the tube as shown in FiGURE 2. In some cases, the screen may be wide enough to provide more than one thickness when expanded and thus increase the strength of the liner. This screen serves a number of functions including holding the resin-impregnated fabric in place and protecting it from injury by contact with the well wall as the sleeve is lowered into the well. Additionally, it provides a longitudinally permeable member around the fabric as the sleeve and liner are being expanded out into contact with the well wall or the casing. Such permeability has been found r particularly desirable since it permits well fluids to escape from underneath the patch and the surplus unset resin carried in the sleeve to flow under pressure in any dircc tion, particularly vertically to the end of the patch or into holes, perforations, or voids in the casing or well wall. This surplus resin is extruded into voids such as the pores of a formation or into holes behind the casing. One particular advantage of the permeable sleeve and especially the outer lamina or screen is that the surplus resin is squeezed through one or more holes 43 or perforations in a casing 44- and forms on the outside of the casing buttons 45 which appear when set to plug the holes so that any reasonable amount of pressure can. be applied externally and the casing liner will not leak or collapse.

Any resin which will cure or set hard, either naturally or artificaliy, in the well may be empioyed. Typically. these resins are thermosetting resins, i.e., resins which are capable of undergoing a permanent physical change under the influence of well temperature or an artificially induced higher temperature. Polyester or epoxy resins are examples. Other suitable resins include urea. resorcinol, and phenol formaldchydes, and the like. Epon 828, an epoxy resin manufactured by Shell Chemical Company, is an example of a preferred epoxy resin. As is well known in this art, thcsc resins may be combined and various catalysts or curing agents employed in various concentrations so that the setting or curing time or pot life for various well depths or various temperatures may be controlled. Versamid resin 140, a polynmide manufactured by General Mills, Inc, is an example of a preferred catalyst which, in the ratio of about 30 parts by volume to 70 parts of the Epon 828 epoxy resin, has a pot life at room temperature of about 34 /2 hours. Such resins when set, i.e., when they are cured suiliciently to be self-supporting and relatively rigid, are referred to herein as plastics.

After the sleeve or patch has thus been made up on the expansible tube and mandrel and the shear plug 23 has been installed and after the relief valve opening pressure has been set as previously described, the mandrel is ready to be lowered into the well. In most cases, however, before the apparatus is lowered into the well, it is desirable to locate accurately or otherwise know the elevation of a hole in the casing, of the casing perforations, or of a lost circulation zone to be sealed so that the liner can be placed at the proper elevation. Once the proper elevation is determined, it is also sometimes desirable to clean the surface where the liner is to be placed as by the use of chemicals or by abrasive means such as a steel brush, or both. The mandrel and sleeve are then lowered into position either on a wire line or a tubing string. As the mandrel is lowered into the liquids in the well, the standing valve member 27 is raised to permit the well fluids to enter the mandrel and the tubing string and thus substantially equalize the pressures inside and outside the tube and prevent it from being collapsed. When the mandrel has been lowered to the proper depth so that the sleeve is located at a position opposite the zone to be lined, fluid is injected into the tubing string and sufficient pressure applied to expand the tube 12, break the fiber binding or tacking, and expand the sleeve 13 out against the surface of the casing or the well wall. Typically, sufiicient pressure is applied to this fluid to produce a bearing pressure of 50-100 or more pounds per square inch between the tube and the wall and to thereby squeeze the unset plastic or resin within the fibers into any voids or holes 43 in the well wall or in casing 44. The amount of pressure applied at the surface will, of course, depend upon the pop-off pressure of the relief valve, the static liquid level within the well, the density of the fluid in the tubing, the depth of the sleeve in the well, etc.

After fluid is injected into the mandrel to expand the tube and the laminated sleeve out against the Wall of the casing or the well, pressure is maintained on the mandrel for several hours, typically from about to about 24 hours, or more, while the resin is cured or set and produces a hard immobile liner. During the time that the tube is thus expanded the liquid level in the well may tend to vary, especially in wells which are not initially at static equilibrium. During this time the pressures above and below the mandrel are equalized by fluid flow through bypass conduit 22 so that the well fluids will not unseat the expanded tube and flush away the unset resin. Where heat is desired to accelerate curing of the resin, a heat source may be lowered through the tubing string to heat the mandrel and adjacent areas,

After the resin has cured sufficiently to produce a selfsupporting strong liner, typically from several hours to a day or more, the setting tool is released by deflating the expanded tube. This may be accomplished by any of a number of means such as by iniecting gas into the tubing string to displace liquid through the relief valve and then releasing the pressure on the tubing string at the surface so that the internal and external pressure on the expansible tube is balanced or otherwise sufiiciently equalized through the standing valve to collapse the rubber tube. In the preferred embodiment, the pressure within the mandrel may be equalized with the external pressure by dropping a go-devil down the tubing. When it strikes the shear plug 23, the plug is broken and a port 42 through the wall of the upper head 18 is opened to permit liquid within the mandrel to flow to the annular space outside the tubing and equalize the pressures inside and outside the resilient tube so that the tube 12 is con tracted by its own resiliency.

With the expansible tube contracted away from the set liner, the tubing string and mandrel are pulled from the well. As they are removed from the well, the liquid within the tubing string discharges through the open port 42 maintaining only a small diiferential pressure between the inside and outside of the mandrel. The resilient tube can, therefore, normally be withdrawn from the well without difliculty and reused as many times as desired.

The thickness of the plastic liner left in the well depends generally upon the number of fabric and screen laminae used in the sleeve. It may vary from about inch to about /2 inch or more but the liner is typically about %-%1 inch thick. The liner thus leaves sufiicient space to permit the mandrel with another sleeve mounted thereon to be run through the well and the liner to a greater depth so that deeper holes or perforations can subsequently be plugged.

From the foregoing, it can be seen that various modifications of the apparatus and procedure can be made without departing from. the spirit of this invention. For example, whereas in the preferred embodiment an apparatus and procedure for placing a plastic patch in a well have been particularly described, I have found that gen erally the same procedure can be employed not only to place a strong plastic patch over a hole or opening in any container, pressure vessel, or the like, but to place a liner in a vessel regardless of whether there is or is not a hole in the wall of the vessel. And whereas in the above description reference has been made to running the mandrel on a tubing string and expanding it by injecting a fluid into the tube through the tubing string, the mandrel can be run on a wire line and in such instance the tube can be expanded either mechanically as by manipulation of the wire line or by an electric motor, or pneumatically as by the use of gas generating chemicals, or the like. 1

Examples of this type of equipment are illustrated in US. Patent 2,781,854, Boer et al; US. Patent 2,842,212, Lebourg; and US. Patent 2,843,052, Andrus. This invention should, therefore, be construed not to be limited by the description which has been given by way of example. vIt should instead be construed to be limited only by the scope of appended claims.

I claim:

1. A method of patching an opening in a container comprising impregnating multiple layers of fabric larger than said opening witha resin adapted to set and form a plastic, placing at least one layer of a woven screen larger than said opening over said opening to provide a permeable path for resin to flow from said fabric through said opening, superimposing at least one layer of said resin-impregnated fabric on said screen, pressing said resin-impregnated fabric and said screen against said opening before said resin has set to displace part of said resin through said screen and thence through said opening so that said resin forms a button on the end of said opening opposite said fabric and said screen, and holding pressure against said resin-impregnated fabric until said resin is set to form a plastic patch over said opening.

2'. A method of lining a cylindrical vessel comprising building up on an expansible tube an expansible sleeve having multiple layers of thermosetting resin-impregnated fabric and an outer layer of woven screen, said resin being adapted to set and form a plastic, inserting said tube and said sleeve into said vessel, injecting fluid into said tube before said resin has set to expand said tube and said sleeve against the wall of said vessel and squeeze said resin through said screen, maintaining said tube under an internal pressure substantially greater than the pressure in said vessel but outside said tube so that said tube and said sleeve will remain in an expanded position until said resin is set sufficiently to form a self-supporting rigid liner in said vessel, equalizing the pressure in said tube with the pressure in said vessel to contract said tube and release it from said liner, and then withdrawing said tube from said vessel.

3. A method of patching a hole in a pressure vessel comprising building up on a resilient tube an expansible sleeve having multiple layers of fabric impregnated with thermosetting resin and an outer layer of woven screen permeable to said resin, said resin containing sufficient catalyst to set to a rigid plastic, inserting said tube and said sleeve into said pressure vessel, injecting fluid into said tube before said resin has set to expand said tube and said sleeve and press said resin-impregnated fabric and said screen against said opening to displace part of said resin through said screen and thence through said hole so that said resin forms a button on the end of said hole opposite said sleeve, maintaining said tube under an internal fluid pressure substantially greater than the pressure in said vessel so that said tube will remain in an expanded position until said resin is set sufldciently to form a selfsupporting rigid liner in said vessel, releasing the pressure within said tube to equalize the pressure therein with the pressure in said vessel and thereby contract said tube and release it from said liner, and then withdrawing said tube from said pressure vessel.

4. A method of setting a plastic liner in a well comprising lowering into said well an expansible mandrel having a resin-impregnated expansible sleeve mounted on a portion of the length thereof, expanding said mandrel into contact with all of said sleeve before said resin has set, to expel some of the resin therefrom into contact with the well here, maintaining all of said sleeve in an expanded position until said resin is set, contracting said mandrel to release it from said sleeve and then withdrawing all of saidmandrel from said well, whereby the sleeve remains bonded to the well bore to form a liner therefor.

5. A method of setting a plastic liner in a well comprising building up on a portion of the length of an expansible mandrel a resin-impregnated expansible sleeve of laminated fiber, said resin being adapted to be cured in said well, lowering said mandrel and said sleeve into said well, expanding said mandrel into contact with all of said sleeve before said resin has set to expel some of the resin therefrom into contact with the well bore, maintaining all of said sleeve in an expanded position until said resin is cured sufficiently to form a self-supporting liner, contracting said mandrel to release it from said sleeve, and then withdrawing all of said mandrel from said well, whereby the sleeve remains bonded to the well bore to form a liner therefor.

6. A method of setting a plastic liner in a well comprising building up on a portion of the length of an expansible tube of a mandrel a thermosetting, resin-impregnating expansible sleeve by applying an inner layer of fabric over said tube and an outer layer of Woven screen over said fabric, said resin being adapted to be cured at the temperaure of said well, lowering said mandrel and said sleeve into said well before said resin has set, expanding said tube into contact with all of said sleeve to expel some of the resin therefrom into contact with the well bore, maintaining said tube and all of said sleeve in an expanded position until said resin is cured sufliciently to form a self-supporting rigid liner, contracting said tube to release it from said sleeve and then withdrawing all of said mandrel from said well, whereby the sleeve remains bonded to the well bore to form a liner therefor.

7. A method of setting a pastie liner in a well comprising buiiding up on a portion of the length of an expansible tube of a mandrel a laminated sleeve of glass cloth and woven screen by applying said glass cloth to said tube and surrounding said glass cloth by said woven screen, impregnating said sleeve with a viscous resin which contains sufiicient catalyst to cure at the temperature of said well and produce a plastic, lowering said mandrel and said sleeve into said well before said resin is cured, injecting fluid into said mandrel to expand said tube into contact with all of said sleeve to expel some of the resin therefrom into contact with the well bore, maintaining said tube under an internal pressure substantially greater than the well pressure at the elevation of said mandrel so that said tube will be in an expanded position until said resin is cured sufliciently to form a selfsupporting rigid liner, releasing the pressure within said mandrel to contact said tube and release it from said sleeve and then withdrawing all of said mandrel from said well, whereby the sleeve remains bonded to the well bore to form a liner therefor.

8. A method of patching a hole in a well casing comprising impregnating multiple layers of fabric larger than said hole with a resin adapted to set and form a plastic, placing at least one layer of a woven screen larger than said hole over said hole to provide a permeable path for resin to fiow from said fabric through said hole, superimposing at least one layer of said resin-impregnated fabric on said screen, pressing said resin-impregnated fabric and said screen against said hole before said resin has set to displace part of said resin through said screen and thence through said hole so that said resin forms a botton on the end of said hole opposite said fabric and said screen, and holding pressure against said resin-impregnated fabric until said resin is set to form a plastic path over said hole.

9. A method of setting a plastic liner in a well casing comprising lowering into said well an cxpansible mandrel having a resin-impregnated expansible sleeve mounted on a portion of the length thereof, expanding said mandrel into contact with all of said sleeve before said resin has set, to expel some of the resin therefrom into contact with the casing bore, maintaining all of said sleeve in an expanded position until said resin is set, contracting said mandrel to release it from said sleeve and then withdrawing all of 'saidmandrel from said Well, whereby the sleeve remains bonded to the casing to form a liner therefor.

References Cited in the file of this patent UNITED STATES PATENTS Limit i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,028,915 April 10, 1962 Earl R. Jennings It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 39, for "vertically" read vertical column 8, line 19 for "botton" rea I? d button Signed and sealed this 28th day of August 1962.

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A METHOD OF PATCHING AN OPENING IN A CONTAINER COMPRISING IMPREGNATING MULTIPLE LAYERS OF FABRIC LARGER THAN SAID OPENING WITH A RESIN ADAPTED TO SET AND FORM A PLASTIC, PLACING AT LEAST ONE LAYER OF A WOVEN SCREEN LARGER THAN SAID OPENING OVER SAID OPENING TO PROVIDE A PERMEABLE PATH FOR RESIN TO FLOW FROM SAID FABRIC THROUGH SAID OPENING SUPERIMPOSING AT LEAST ONE LAYER OF SAID RESIN-IMPREGNATED FABRIC ON SAID SCREEN PRESSING SAID RESIN-IMPREGNATED FABRIC AND SAID SCREEN AGAINST SAID OPENING BEFORE SAID RESIN HAS SET TO DISPLACE PART OF SAID RESIN THROUGH SAID SCREEN AND THENCE THROUGH SAID OPENING SO THAT RESIN FORMS A BUTTON ON THE END OF SAID OPENING OPPOSITE SAID FABRIC AND SAID SCREEN, AND HOLDING PRESSURE AGAINST SAID RESIN-IMPREGNATED FABRIC UNTIL SAID RESIN IS SET TO FORM A PLASTIC PATCH OVER SAID OPENING. 